The invention relates to a holding and releasing mechanism for holding and releasing a cable take-up device of a step shifter, for example, and a step shifter comprising the holding and releasing mechanism, as well as a system which in turn comprises the step shifter.
Step shifters in which a holding and releasing mechanism—according to the invention can be used are particularly useful in bicycles. They can assist the user of the bicycle to wind and release the shifting cable step-by-step wherein the actuating levers generally return back to the initial position after they are actuated. The term “trigger switch” or “trigger shifter” may be used interchangeably for step shifter.
Step shifters, or trigger switches, are known from patent specifications EP 0 361 335 B1, EP 1 232 940 B2, EP 1 366 981 B1 and FR 2 701 917 A1, among others.
Known step shifters each comprise a cable pull-up or winding mechanism for the shifting cable as well as a mechanism for holding and releasing the shifting cable. The present invention relates to an especially advantageous embodiment of a holding and releasing mechanism as well as a step shifter in which this holding and releasing mechanism is used, as well as a shifting system in which this step shifter is in turn used.
The holding and releasing mechanism of EP 0 361 335 B1 comprises first and second locking elements that pivot in opposite directions for alternatingly engaging into a toothed locking disk. In a release, the locking element presently engaged with the locking disk is disengaged out from the locking disk. The locking disk can now rotate until the other respective locking element engages with the locking teeth. When the release handle is returned back to its initial position, the second locking element moves out of engagement with the locking disk and the locking disk moves until it re-engages the first locking element.
A holding and releasing mechanism is known from EP 1 232 940 B2. Here, a pivotable locking latch has a locking catch which initially engages with a first tooth of a locking disk, which fixes the locking disk. When the locking catch is now pivoted out of the engagement area of the first tooth, the locking disk can be rotated to the point that a tooth of the locking disk adjacent to the first tooth comes into engagement with a safety catch of the latch which is pivoted at the same time into the engagement area of the teeth. If the locking latch is now pivoted back to its initial position, the locking toothed disk can rotate further until the locking catch of the locking latch comes into engagement with a third tooth which is also adjacent to the first tooth, the locking toothed disk being held there again.
Another holding and releasing mechanism is known from EP 1 366 981 B1 in which a slidingly held locking latch engages alternatingly with locking and safety teeth disposed on opposite sides of a locking toothed disk when a release lever is actuated.
Finally, also known from FR 2 701 917 A1 is a holding and releasing mechanism in which a locking latch initially engages with a locking tooth by way of a locking catch. When a release lever is actuated, the locking latch pivots such that the locking catch comes out of engagement with the locking tooth, whereupon a safety catch of the latch comes into engagement with a safety tooth while the locking toothed disk has rotated by a specific angular amount. When the locking latch is pivoted back, the locking catch thereof re-engages with a locking tooth.